1. Field of the Invention
Power drive transmission assembly.
2. Description of the Prior Art
In the past, various power operated assemblies have been proposed and used in an attempt to automatically control the pitch diameter ratios of a driving and driven pulley connected by a V-belt in accordance with the rate of rotation imposed on one of the pulleys. Such prior art devices have, in the main, utilized centrifugal means to attempt to accomplish this result, but such centrifugal means are effective in but a limited range, and have the disadvantage that they impart a radial imbalance to the system.
The primary purpose in devising the present invention is to supply a power drive transmission assembly which can be automatically or manually controlled to provide a desired pitch diameter ratio to the driving and driven pulleys engaged by an endless V-belt. This ratio is achieved by varying the pitch diameter of the driving pulley only, and the pitch diameter of the driven pulley automatically varying in accordance therewith due to the spring loaded structure of the driven pulley. The change of the effective pitch diameter of the driving pulley only is accomplished by moving a second portion thereof relative to a first portion, which increases or decreases the pitch diameter of the driving pulley. The pitch diameter of the driven pulley is also controlled by the belt tension, and the magnitude of the spring loading on the second half portion of the driven pulley.
A major object of the present invention is to provide a power transmission assembly for a prime mover, such as an internal combustion engine, which assembly may be so adjusted that a driving pulley, driven pulley and connecting V-belt that form a part thereof are so controlled and so cooperate with power means and a sensing device that detect both the rate of rotation and the lateral position of a second movable half portion of the driving pulley relative to a half portion that rotates in a fixed position on the driving shaft, that the power means is energized to vary the lateral spacing between the first and second half portions of the driving pulley that a desired pitch diameter ratio is achieved between the driving and driven pulleys. As the lateral spacing between the first and second half portions of the driving pulley is varied, the tension on the V-belt is increased or decreased, and the effective diameter of the driven pulley is varied by laterally moving a second spring loaded second portion thereof relative to a first portion of the driven pulley that is rigidly secured to the driven shaft, with the ratio between the pitch diameter of the driving and driven pulleys when the invention is operating at all times has a desired relationship to the torque curve of the prime mover.
Another object of the invention is to supply a power transmission assembly that when in operation effects an infinite number of variations in the effective pitch dimeter ratio of the driving and driven pulleys without loss of power, is at all times in radial balance, requires no radially movable parts or weights and in effect uniformly shifting the pitch diameter ratio of the driving and driven pulleys without being dependent on the rate of rotation of the driving pulley.
A further object of the invention is to supply a power transmission assembly that is easily and conveniently adjusted to a particular torque curve of a particular engine or prime mover, and when so adjusted will continue to automatically have a desired relationship to the torque curve of the engine as the driven pulley is subjected to varying loads.
Another object of the present invention is to supply a power drive transmission that has a broad capability to accept a wide variation of engine drive speeds, horse power, and torque output, and permit greater efficiency to be obtained from the engine inasmuch as the power drive assembly does not require the capability to sense torque being applied to the driven pulley.
Yet another object of the invention is to furnish a power transmission assembly that permits upward and downward shifting of the pitch diameter ratios of the driving and driven pulleys without the driving force being disengaged therefrom.